一种基坑钢支撑预应力施加数值模拟方法研究
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摘要
在FLAC3D中,采用梁单元模拟基坑钢支撑时,现有的预应力施加模拟方法是在梁单元设置以后,通过对梁单元两端的节点施加一对相反的作用力来代表要施加的预应力,导致支撑预应力变为围护体系的外力这一与实际不符的情况发生。为此,本文根据钢支撑与围护结构相互作用的机理,提出一种改进的钢支撑预应力施加模拟方法—虚拟位移法,即先固定梁单元一端节点,另一端节点施加节点虚拟位移,虚拟位移再施加于梁单元上,使梁单元压缩形成预应力。以深圳地铁5号线前海湾站基坑工程为背景,进行了常规方法和虚拟位移法的比较:在对支撑结构的影响上,常规方法引起各道支撑的轴力变化与实际存在明显的差别,而虚拟位移法则与实际一致。本文工作有实际意义。
In FLAC3D,a pair of contrary forces used as prestress are applied at the end nodes of beam element when steel support of foundation pit is simulated using beam element according to existing methods,which makes strut prestressing turn into external force of enclosure system,and this is quite different from that in actual situation.Thus,an improved simulating method,named virtual displacement,is proposed in this paper based on the mechanism of interaction between steel support and bracing structure.Firstly,one end of the beam element is fixed and on the other end a node rate is applied to form node virtual displacement,then the virtual displacement is applied on beam element to make it compressed and the prestress is formed.In this paper the routine method is compared with Virtual displacement method under the background of foundation pit project in the Qianhaiwan Station of Shenzhen Metro Line 5: about the affection on the support structure,the axial force change of each support structure calculated by traditional method is obviously different from that under actual condition,but the result by virtual displacement method consistent with that in practice.
In FLAC3D,a pair of contrary forces used as prestress are applied at the end nodes of beam element when steel support of foundation pit is simulated using beam element according to existing methods,which makes strut prestressing turn into external force of enclosure system,and this is quite different from that in actual situation.Thus,an improved simulating method,named virtual displacement,is proposed in this paper based on the mechanism of interaction between steel support and bracing structure.Firstly,one end of the beam element is fixed and on the other end a node rate is applied to form node virtual displacement,then the virtual displacement is applied on beam element to make it compressed and the prestress is formed.In this paper the routine method is compared with Virtual displacement method under the background of foundation pit project in the Qianhaiwan Station of Shenzhen Metro Line 5: about the affection on the support structure,the axial force change of each support structure calculated by traditional method is obviously different from that under actual condition,but the result by virtual displacement method consistent with that in practice.
引文
[1]任建喜,张引合,张琨,等.西安地铁车站深基坑变形规律FLAC模拟研究[J].铁道工程学报,2011,(3):90-93.(Ren Jianxi,Zhang Yinhe,Zhang Kun,et al.Research on the deformation law of deep foundation pitof metro station in Xi’an by FLAC simulation[J].Jour-nal of Railway Engineering Society,2011,(3):90-93.(in Chinese))
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[5]鲁涛.基于FLAC～(3D)的某碎石土边坡地震反应分析[J].中国农村水利水电,2011,(7):96-100.(Lu Tao.An analysis of the seismic response of debrisslope based on FLAC～(3d)[J].China Rural Waterand Hydropower,2011,(7):96-100.(in Chinese))
[6]欧湘萍,白楷,朱云升,等.基于FLAC-3D的强度折减法边坡稳定性分析[J].武汉理工大学学报,2009,31(9):59-61.(Ou Xiangping,Bai Kai,Zhu Yunsheng,etal.The strength reduction method for stability analysis ofslope based on FLAC-3D[J].Journal of Wuhan Univer-sity of Technology,2009,31(9):59-61.(in Chinese))
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[8]孙克国,李术才,李树忱,等.明挖法地铁车站围护结构变形模拟与预测研究[J].岩石力学与工程学报,2008,27(增1),3 210-3 215.(Sun Keguo,Li Shucai,Li Shuchen,et al.Simulation and prediction research ofenclosure structure deformation for an open-cut metrostation[J].Chinese Journal of Rock Mechanics and En-gineering,2008,27(Supp.1),3 210-3 215.(in Chi-nese))
[9]刘继国,曾亚武.FLAC3D在深基坑开挖与支护数值模拟中的应用[J].岩土力学,2006,27(3):505-508.(Liu Jiguo,Zeng Yawu.Application of FLAC3D to sim-ulation of foundation excavation and support[J].Rockand Soil Mechanics,2006,27(3):505-508.(in Chi-nese))
[10]陈敏华,陈增新,张长生.FLAC在基坑开挖分析中的应用[J].岩土工程学报,2006,28(增1):1437-1 440.(Chen Minhua,Chen Zengxin,Zhang Changsh-eng.Application of FLAC in analysis of foundation ex-cavation[J].Chinese Journal of Geotechnical Engineer-ing,2006,28(Supp.1):1 437-1 440.(in Chinese))
[11]池鹏.深基坑围护结构变形规律监测及其优化研究[D].西安:西安科技大学,2008.(Chi Peng.Re-search on field monitoring of deformation rule about sup-port structure and it’s optimization in deep foundationfit engineering[D].Xi’an:Xi’an University of Scienceand Technology,2008.(in Chinese))
[12]高立新.地铁车站深基坑变形规律监测及FLAC模拟研究[D].西安:西安科技大学,2009.(Gao Lixin.Monitoring and FLAC simulation study of deformationlaws of deep excavation in subway station[D].Xi’an:Xi’an University of Science and Technology,2009.(inChinese))
[2]陈敏华,陈增新,张长生.FLAC在基坑开挖分析中的应用[J].岩土工程学报,2006,11(28):1437-1 440.(Chen Minhua,Chen Zengxin,Zhang Changsh-eng.Application of FLAC in analysis of foundation ex-cavation[J].Chinese Journal of Geotechnical Engineer-ing,2006,11(28):1 437-1 440.(in Chinese))
[3]M.Azadi,S.M.Mir Mohammad Hosseini.The uplif-ting behavior of shallow tunnels within the liquefiablesoils under cyclic loadings[J].Tunnelling and Under-ground Space Technology,2010,25:158-167.
[4]黄润秋,肖华波.偏压连拱隧道施工过程优化的FLAC～(3D)分析[J].成都理工大学学报(自然科学版),2009,36(1):59-66.(Huang Runqiu,XiaoHuabo.An optimum analysis of the construction processfor double-arch tunnels under an unsymmetrical pres-sures and complex geological conditions[J].Journal ofChengdu University of Technology(Science&Technolo-gy Edition),2009,36(1):59-66.(in Chinese))
[5]鲁涛.基于FLAC～(3D)的某碎石土边坡地震反应分析[J].中国农村水利水电,2011,(7):96-100.(Lu Tao.An analysis of the seismic response of debrisslope based on FLAC～(3d)[J].China Rural Waterand Hydropower,2011,(7):96-100.(in Chinese))
[6]欧湘萍,白楷,朱云升,等.基于FLAC-3D的强度折减法边坡稳定性分析[J].武汉理工大学学报,2009,31(9):59-61.(Ou Xiangping,Bai Kai,Zhu Yunsheng,etal.The strength reduction method for stability analysis ofslope based on FLAC-3D[J].Journal of Wuhan Univer-sity of Technology,2009,31(9):59-61.(in Chinese))
[7]杨宝珠,仲晓梅.基于FLAC-3D的深基坑开挖过程数值分析[J].河北工程大学学报(自然科学版),2008,25(3):15-18.(Yang Baozhu,Zhong Xiaomei.Numerical analysis of deep excavation on FLAC-3D[J].Journal of Hebei University of Engineering(Natural Sci-ence Edition),2008,25(3):15-18.(in Chinese))
[8]孙克国,李术才,李树忱,等.明挖法地铁车站围护结构变形模拟与预测研究[J].岩石力学与工程学报,2008,27(增1),3 210-3 215.(Sun Keguo,Li Shucai,Li Shuchen,et al.Simulation and prediction research ofenclosure structure deformation for an open-cut metrostation[J].Chinese Journal of Rock Mechanics and En-gineering,2008,27(Supp.1),3 210-3 215.(in Chi-nese))
[9]刘继国,曾亚武.FLAC3D在深基坑开挖与支护数值模拟中的应用[J].岩土力学,2006,27(3):505-508.(Liu Jiguo,Zeng Yawu.Application of FLAC3D to sim-ulation of foundation excavation and support[J].Rockand Soil Mechanics,2006,27(3):505-508.(in Chi-nese))
[10]陈敏华,陈增新,张长生.FLAC在基坑开挖分析中的应用[J].岩土工程学报,2006,28(增1):1437-1 440.(Chen Minhua,Chen Zengxin,Zhang Changsh-eng.Application of FLAC in analysis of foundation ex-cavation[J].Chinese Journal of Geotechnical Engineer-ing,2006,28(Supp.1):1 437-1 440.(in Chinese))
[11]池鹏.深基坑围护结构变形规律监测及其优化研究[D].西安:西安科技大学,2008.(Chi Peng.Re-search on field monitoring of deformation rule about sup-port structure and it’s optimization in deep foundationfit engineering[D].Xi’an:Xi’an University of Scienceand Technology,2008.(in Chinese))
[12]高立新.地铁车站深基坑变形规律监测及FLAC模拟研究[D].西安:西安科技大学,2009.(Gao Lixin.Monitoring and FLAC simulation study of deformationlaws of deep excavation in subway station[D].Xi’an:Xi’an University of Science and Technology,2009.(inChinese))
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